lockdep_proc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * kernel/lockdep_proc.c
   4  *
   5  * Runtime locking correctness validator
   6  *
   7  * Started by Ingo Molnar:
   8  *
   9  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  10  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
  11  *
  12  * Code for /proc/lockdep and /proc/lockdep_stats:
  13  *
  14  */
  15 #include <linux/export.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/seq_file.h>
  18 #include <linux/kallsyms.h>
  19 #include <linux/debug_locks.h>
  20 #include <linux/vmalloc.h>
  21 #include <linux/sort.h>
  22 #include <linux/uaccess.h>
  23 #include <asm/div64.h>
  24
  25 #include "lockdep_internals.h"
  26
  27 /*
  28  * Since iteration of lock_classes is done without holding the lockdep lock,
  29  * it is not safe to iterate all_lock_classes list directly as the iteration
  30  * may branch off to free_lock_classes or the zapped list. Iteration is done
  31  * directly on the lock_classes array by checking the lock_classes_in_use
  32  * bitmap and max_lock_class_idx.
  33  */
  34 #define iterate_lock_classes(idx, class)                                \
  35         for (idx = 0, class = lock_classes; idx <= max_lock_class_idx;  \
  36              idx++, class++)
  37
  38 static void *l_next(struct seq_file *m, void *v, loff_t *pos)
  39 {
  40         struct lock_class *class = v;
  41
  42         ++class;
  43         *pos = class - lock_classes;
  44         return (*pos > max_lock_class_idx) ? NULL : class;
  45 }
  46
  47 static void *l_start(struct seq_file *m, loff_t *pos)
  48 {
  49         unsigned long idx = *pos;
  50
  51         if (idx > max_lock_class_idx)
  52                 return NULL;
  53         return lock_classes + idx;
  54 }
  55
  56 static void l_stop(struct seq_file *m, void *v)
  57 {
  58 }
  59
  60 static void print_name(struct seq_file *m, struct lock_class *class)
  61 {
  62         char str[KSYM_NAME_LEN];
  63         const char *name = class->name;
  64
  65         if (!name) {
  66                 name = __get_key_name(class->key, str);
  67                 seq_printf(m, "%s", name);
  68         } else{
  69                 seq_printf(m, "%s", name);
  70                 if (class->name_version > 1)
  71                         seq_printf(m, "#%d", class->name_version);
  72                 if (class->subclass)
  73                         seq_printf(m, "/%d", class->subclass);
  74         }
  75 }
  76
  77 static int l_show(struct seq_file *m, void *v)
  78 {
  79         struct lock_class *class = v;
  80         struct lock_list *entry;
  81         char usage[LOCK_USAGE_CHARS];
  82         int idx = class - lock_classes;
  83
  84         if (v == lock_classes)
  85                 seq_printf(m, "all lock classes:\n");
  86
  87         if (!test_bit(idx, lock_classes_in_use))
  88                 return 0;
  89
  90         seq_printf(m, "%p", class->key);
  91 #ifdef CONFIG_DEBUG_LOCKDEP
  92         seq_printf(m, " OPS:%8ld", debug_class_ops_read(class));
  93 #endif
  94 #ifdef CONFIG_PROVE_LOCKING
  95         seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class));
  96         seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class));
  97 #endif
  98
  99         get_usage_chars(class, usage);
 100         seq_printf(m, " %s", usage);
 101
 102         seq_printf(m, ": ");
 103         print_name(m, class);
 104         seq_puts(m, "\n");
 105
 106         list_for_each_entry(entry, &class->locks_after, entry) {
 107                 if (entry->distance == 1) {
 108                         seq_printf(m, " -> [%p] ", entry->class->key);
 109                         print_name(m, entry->class);
 110                         seq_puts(m, "\n");
 111                 }
 112         }
 113         seq_puts(m, "\n");
 114
 115         return 0;
 116 }
 117
 118 static const struct seq_operations lockdep_ops = {
 119         .start  = l_start,
 120         .next   = l_next,
 121         .stop   = l_stop,
 122         .show   = l_show,
 123 };
 124
 125 #ifdef CONFIG_PROVE_LOCKING
 126 static void *lc_start(struct seq_file *m, loff_t *pos)
 127 {
 128         if (*pos < 0)
 129                 return NULL;
 130
 131         if (*pos == 0)
 132                 return SEQ_START_TOKEN;
 133
 134         return lock_chains + (*pos - 1);
 135 }
 136
 137 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
 138 {
 139         *pos = lockdep_next_lockchain(*pos - 1) + 1;
 140         return lc_start(m, pos);
 141 }
 142
 143 static void lc_stop(struct seq_file *m, void *v)
 144 {
 145 }
 146
 147 static int lc_show(struct seq_file *m, void *v)
 148 {
 149         struct lock_chain *chain = v;
 150         struct lock_class *class;
 151         int i;
 152         static const char * const irq_strs[] = {
 153                 [0]                          = "0",
 154                 [LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq",
 155                 [LOCK_CHAIN_SOFTIRQ_CONTEXT] = "softirq",
 156                 [LOCK_CHAIN_SOFTIRQ_CONTEXT|
 157                  LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq|softirq",
 158         };
 159
 160         if (v == SEQ_START_TOKEN) {
 161                 if (!nr_free_chain_hlocks)
 162                         seq_printf(m, "(buggered) ");
 163                 seq_printf(m, "all lock chains:\n");
 164                 return 0;
 165         }
 166
 167         seq_printf(m, "irq_context: %s\n", irq_strs[chain->irq_context]);
 168
 169         for (i = 0; i < chain->depth; i++) {
 170                 class = lock_chain_get_class(chain, i);
 171                 if (!class->key)
 172                         continue;
 173
 174                 seq_printf(m, "[%p] ", class->key);
 175                 print_name(m, class);
 176                 seq_puts(m, "\n");
 177         }
 178         seq_puts(m, "\n");
 179
 180         return 0;
 181 }
 182
 183 static const struct seq_operations lockdep_chains_ops = {
 184         .start  = lc_start,
 185         .next   = lc_next,
 186         .stop   = lc_stop,
 187         .show   = lc_show,
 188 };
 189 #endif /* CONFIG_PROVE_LOCKING */
 190
 191 static void lockdep_stats_debug_show(struct seq_file *m)
 192 {
 193 #ifdef CONFIG_DEBUG_LOCKDEP
 194         unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
 195                            hi2 = debug_atomic_read(hardirqs_off_events),
 196                            hr1 = debug_atomic_read(redundant_hardirqs_on),
 197                            hr2 = debug_atomic_read(redundant_hardirqs_off),
 198                            si1 = debug_atomic_read(softirqs_on_events),
 199                            si2 = debug_atomic_read(softirqs_off_events),
 200                            sr1 = debug_atomic_read(redundant_softirqs_on),
 201                            sr2 = debug_atomic_read(redundant_softirqs_off);
 202
 203         seq_printf(m, " chain lookup misses:           %11llu\n",
 204                 debug_atomic_read(chain_lookup_misses));
 205         seq_printf(m, " chain lookup hits:             %11llu\n",
 206                 debug_atomic_read(chain_lookup_hits));
 207         seq_printf(m, " cyclic checks:                 %11llu\n",
 208                 debug_atomic_read(nr_cyclic_checks));
 209         seq_printf(m, " redundant checks:              %11llu\n",
 210                 debug_atomic_read(nr_redundant_checks));
 211         seq_printf(m, " redundant links:               %11llu\n",
 212                 debug_atomic_read(nr_redundant));
 213         seq_printf(m, " find-mask forwards checks:     %11llu\n",
 214                 debug_atomic_read(nr_find_usage_forwards_checks));
 215         seq_printf(m, " find-mask backwards checks:    %11llu\n",
 216                 debug_atomic_read(nr_find_usage_backwards_checks));
 217
 218         seq_printf(m, " hardirq on events:             %11llu\n", hi1);
 219         seq_printf(m, " hardirq off events:            %11llu\n", hi2);
 220         seq_printf(m, " redundant hardirq ons:         %11llu\n", hr1);
 221         seq_printf(m, " redundant hardirq offs:        %11llu\n", hr2);
 222         seq_printf(m, " softirq on events:             %11llu\n", si1);
 223         seq_printf(m, " softirq off events:            %11llu\n", si2);
 224         seq_printf(m, " redundant softirq ons:         %11llu\n", sr1);
 225         seq_printf(m, " redundant softirq offs:        %11llu\n", sr2);
 226 #endif
 227 }
 228
 229 static int lockdep_stats_show(struct seq_file *m, void *v)
 230 {
 231         unsigned long nr_unused = 0, nr_uncategorized = 0,
 232                       nr_irq_safe = 0, nr_irq_unsafe = 0,
 233                       nr_softirq_safe = 0, nr_softirq_unsafe = 0,
 234                       nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
 235                       nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
 236                       nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
 237                       nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
 238                       sum_forward_deps = 0;
 239
 240 #ifdef CONFIG_PROVE_LOCKING
 241         struct lock_class *class;
 242         unsigned long idx;
 243
 244         iterate_lock_classes(idx, class) {
 245                 if (!test_bit(idx, lock_classes_in_use))
 246                         continue;
 247
 248                 if (class->usage_mask == 0)
 249                         nr_unused++;
 250                 if (class->usage_mask == LOCKF_USED)
 251                         nr_uncategorized++;
 252                 if (class->usage_mask & LOCKF_USED_IN_IRQ)
 253                         nr_irq_safe++;
 254                 if (class->usage_mask & LOCKF_ENABLED_IRQ)
 255                         nr_irq_unsafe++;
 256                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
 257                         nr_softirq_safe++;
 258                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
 259                         nr_softirq_unsafe++;
 260                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
 261                         nr_hardirq_safe++;
 262                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
 263                         nr_hardirq_unsafe++;
 264                 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
 265                         nr_irq_read_safe++;
 266                 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
 267                         nr_irq_read_unsafe++;
 268                 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
 269                         nr_softirq_read_safe++;
 270                 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
 271                         nr_softirq_read_unsafe++;
 272                 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
 273                         nr_hardirq_read_safe++;
 274                 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
 275                         nr_hardirq_read_unsafe++;
 276
 277                 sum_forward_deps += lockdep_count_forward_deps(class);
 278         }
 279
 280 #ifdef CONFIG_DEBUG_LOCKDEP
 281         DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
 282 #endif
 283
 284 #endif
 285         seq_printf(m, " lock-classes:                  %11lu [max: %lu]\n",
 286                         nr_lock_classes, MAX_LOCKDEP_KEYS);
 287         seq_printf(m, " direct dependencies:           %11lu [max: %lu]\n",
 288                         nr_list_entries, MAX_LOCKDEP_ENTRIES);
 289         seq_printf(m, " indirect dependencies:         %11lu\n",
 290                         sum_forward_deps);
 291
 292         /*
 293          * Total number of dependencies:
 294          *
 295          * All irq-safe locks may nest inside irq-unsafe locks,
 296          * plus all the other known dependencies:
 297          */
 298         seq_printf(m, " all direct dependencies:       %11lu\n",
 299                         nr_irq_unsafe * nr_irq_safe +
 300                         nr_hardirq_unsafe * nr_hardirq_safe +
 301                         nr_list_entries);
 302
 303 #ifdef CONFIG_PROVE_LOCKING
 304         seq_printf(m, " dependency chains:             %11lu [max: %lu]\n",
 305                         lock_chain_count(), MAX_LOCKDEP_CHAINS);
 306         seq_printf(m, " dependency chain hlocks used:  %11lu [max: %lu]\n",
 307                         MAX_LOCKDEP_CHAIN_HLOCKS -
 308                         (nr_free_chain_hlocks + nr_lost_chain_hlocks),
 309                         MAX_LOCKDEP_CHAIN_HLOCKS);
 310         seq_printf(m, " dependency chain hlocks lost:  %11u\n",
 311                         nr_lost_chain_hlocks);
 312 #endif
 313
 314 #ifdef CONFIG_TRACE_IRQFLAGS
 315         seq_printf(m, " in-hardirq chains:             %11u\n",
 316                         nr_hardirq_chains);
 317         seq_printf(m, " in-softirq chains:             %11u\n",
 318                         nr_softirq_chains);
 319 #endif
 320         seq_printf(m, " in-process chains:             %11u\n",
 321                         nr_process_chains);
 322         seq_printf(m, " stack-trace entries:           %11lu [max: %lu]\n",
 323                         nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
 324 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
 325         seq_printf(m, " number of stack traces:        %11llu\n",
 326                    lockdep_stack_trace_count());
 327         seq_printf(m, " number of stack hash chains:   %11llu\n",
 328                    lockdep_stack_hash_count());
 329 #endif
 330         seq_printf(m, " combined max dependencies:     %11u\n",
 331                         (nr_hardirq_chains + 1) *
 332                         (nr_softirq_chains + 1) *
 333                         (nr_process_chains + 1)
 334         );
 335         seq_printf(m, " hardirq-safe locks:            %11lu\n",
 336                         nr_hardirq_safe);
 337         seq_printf(m, " hardirq-unsafe locks:          %11lu\n",
 338                         nr_hardirq_unsafe);
 339         seq_printf(m, " softirq-safe locks:            %11lu\n",
 340                         nr_softirq_safe);
 341         seq_printf(m, " softirq-unsafe locks:          %11lu\n",
 342                         nr_softirq_unsafe);
 343         seq_printf(m, " irq-safe locks:                %11lu\n",
 344                         nr_irq_safe);
 345         seq_printf(m, " irq-unsafe locks:              %11lu\n",
 346                         nr_irq_unsafe);
 347
 348         seq_printf(m, " hardirq-read-safe locks:       %11lu\n",
 349                         nr_hardirq_read_safe);
 350         seq_printf(m, " hardirq-read-unsafe locks:     %11lu\n",
 351                         nr_hardirq_read_unsafe);
 352         seq_printf(m, " softirq-read-safe locks:       %11lu\n",
 353                         nr_softirq_read_safe);
 354         seq_printf(m, " softirq-read-unsafe locks:     %11lu\n",
 355                         nr_softirq_read_unsafe);
 356         seq_printf(m, " irq-read-safe locks:           %11lu\n",
 357                         nr_irq_read_safe);
 358         seq_printf(m, " irq-read-unsafe locks:         %11lu\n",
 359                         nr_irq_read_unsafe);
 360
 361         seq_printf(m, " uncategorized locks:           %11lu\n",
 362                         nr_uncategorized);
 363         seq_printf(m, " unused locks:                  %11lu\n",
 364                         nr_unused);
 365         seq_printf(m, " max locking depth:             %11u\n",
 366                         max_lockdep_depth);
 367 #ifdef CONFIG_PROVE_LOCKING
 368         seq_printf(m, " max bfs queue depth:           %11u\n",
 369                         max_bfs_queue_depth);
 370 #endif
 371         seq_printf(m, " max lock class index:          %11lu\n",
 372                         max_lock_class_idx);
 373         lockdep_stats_debug_show(m);
 374         seq_printf(m, " debug_locks:                   %11u\n",
 375                         debug_locks);
 376
 377         /*
 378          * Zappped classes and lockdep data buffers reuse statistics.
 379          */
 380         seq_puts(m, "\n");
 381         seq_printf(m, " zapped classes:                %11lu\n",
 382                         nr_zapped_classes);
 383 #ifdef CONFIG_PROVE_LOCKING
 384         seq_printf(m, " zapped lock chains:            %11lu\n",
 385                         nr_zapped_lock_chains);
 386         seq_printf(m, " large chain blocks:            %11u\n",
 387                         nr_large_chain_blocks);
 388 #endif
 389         return 0;
 390 }
 391
 392 #ifdef CONFIG_LOCK_STAT
 393
 394 struct lock_stat_data {
 395         struct lock_class *class;
 396         struct lock_class_stats stats;
 397 };
 398
 399 struct lock_stat_seq {
 400         struct lock_stat_data *iter_end;
 401         struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
 402 };
 403
 404 /*
 405  * sort on absolute number of contentions
 406  */
 407 static int lock_stat_cmp(const void *l, const void *r)
 408 {
 409         const struct lock_stat_data *dl = l, *dr = r;
 410         unsigned long nl, nr;
 411
 412         nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
 413         nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
 414
 415         return nr - nl;
 416 }
 417
 418 static void seq_line(struct seq_file *m, char c, int offset, int length)
 419 {
 420         int i;
 421
 422         for (i = 0; i < offset; i++)
 423                 seq_puts(m, " ");
 424         for (i = 0; i < length; i++)
 425                 seq_printf(m, "%c", c);
 426         seq_puts(m, "\n");
 427 }
 428
 429 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
 430 {
 431         s64 div;
 432         s32 rem;
 433
 434         nr += 5; /* for display rounding */
 435         div = div_s64_rem(nr, 1000, &rem);
 436         snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
 437 }
 438
 439 static void seq_time(struct seq_file *m, s64 time)
 440 {
 441         char num[15];
 442
 443         snprint_time(num, sizeof(num), time);
 444         seq_printf(m, " %14s", num);
 445 }
 446
 447 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
 448 {
 449         seq_printf(m, "%14lu", lt->nr);
 450         seq_time(m, lt->min);
 451         seq_time(m, lt->max);
 452         seq_time(m, lt->total);
 453         seq_time(m, lt->nr ? div64_u64(lt->total, lt->nr) : 0);
 454 }
 455
 456 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 457 {
 458         const struct lockdep_subclass_key *ckey;
 459         struct lock_class_stats *stats;
 460         struct lock_class *class;
 461         const char *cname;
 462         int i, namelen;
 463         char name[39];
 464
 465         class = data->class;
 466         stats = &data->stats;
 467
 468         namelen = 38;
 469         if (class->name_version > 1)
 470                 namelen -= 2; /* XXX truncates versions > 9 */
 471         if (class->subclass)
 472                 namelen -= 2;
 473
 474         rcu_read_lock_sched();
 475         cname = rcu_dereference_sched(class->name);
 476         ckey  = rcu_dereference_sched(class->key);
 477
 478         if (!cname && !ckey) {
 479                 rcu_read_unlock_sched();
 480                 return;
 481
 482         } else if (!cname) {
 483                 char str[KSYM_NAME_LEN];
 484                 const char *key_name;
 485
 486                 key_name = __get_key_name(ckey, str);
 487                 snprintf(name, namelen, "%s", key_name);
 488         } else {
 489                 snprintf(name, namelen, "%s", cname);
 490         }
 491         rcu_read_unlock_sched();
 492
 493         namelen = strlen(name);
 494         if (class->name_version > 1) {
 495                 snprintf(name+namelen, 3, "#%d", class->name_version);
 496                 namelen += 2;
 497         }
 498         if (class->subclass) {
 499                 snprintf(name+namelen, 3, "/%d", class->subclass);
 500                 namelen += 2;
 501         }
 502
 503         if (stats->write_holdtime.nr) {
 504                 if (stats->read_holdtime.nr)
 505                         seq_printf(m, "%38s-W:", name);
 506                 else
 507                         seq_printf(m, "%40s:", name);
 508
 509                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
 510                 seq_lock_time(m, &stats->write_waittime);
 511                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
 512                 seq_lock_time(m, &stats->write_holdtime);
 513                 seq_puts(m, "\n");
 514         }
 515
 516         if (stats->read_holdtime.nr) {
 517                 seq_printf(m, "%38s-R:", name);
 518                 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
 519                 seq_lock_time(m, &stats->read_waittime);
 520                 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
 521                 seq_lock_time(m, &stats->read_holdtime);
 522                 seq_puts(m, "\n");
 523         }
 524
 525         if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
 526                 return;
 527
 528         if (stats->read_holdtime.nr)
 529                 namelen += 2;
 530
 531         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 532                 char ip[32];
 533
 534                 if (class->contention_point[i] == 0)
 535                         break;
 536
 537                 if (!i)
 538                         seq_line(m, '-', 40-namelen, namelen);
 539
 540                 snprintf(ip, sizeof(ip), "[<%p>]",
 541                                 (void *)class->contention_point[i]);
 542                 seq_printf(m, "%40s %14lu %29s %pS\n",
 543                            name, stats->contention_point[i],
 544                            ip, (void *)class->contention_point[i]);
 545         }
 546         for (i = 0; i < LOCKSTAT_POINTS; i++) {
 547                 char ip[32];
 548
 549                 if (class->contending_point[i] == 0)
 550                         break;
 551
 552                 if (!i)
 553                         seq_line(m, '-', 40-namelen, namelen);
 554
 555                 snprintf(ip, sizeof(ip), "[<%p>]",
 556                                 (void *)class->contending_point[i]);
 557                 seq_printf(m, "%40s %14lu %29s %pS\n",
 558                            name, stats->contending_point[i],
 559                            ip, (void *)class->contending_point[i]);
 560         }
 561         if (i) {
 562                 seq_puts(m, "\n");
 563                 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
 564                 seq_puts(m, "\n");
 565         }
 566 }
 567
 568 static void seq_header(struct seq_file *m)
 569 {
 570         seq_puts(m, "lock_stat version 0.4\n");
 571
 572         if (unlikely(!debug_locks))
 573                 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
 574
 575         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 576         seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
 577                         "%14s %14s\n",
 578                         "class name",
 579                         "con-bounces",
 580                         "contentions",
 581                         "waittime-min",
 582                         "waittime-max",
 583                         "waittime-total",
 584                         "waittime-avg",
 585                         "acq-bounces",
 586                         "acquisitions",
 587                         "holdtime-min",
 588                         "holdtime-max",
 589                         "holdtime-total",
 590                         "holdtime-avg");
 591         seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
 592         seq_printf(m, "\n");
 593 }
 594
 595 static void *ls_start(struct seq_file *m, loff_t *pos)
 596 {
 597         struct lock_stat_seq *data = m->private;
 598         struct lock_stat_data *iter;
 599
 600         if (*pos == 0)
 601                 return SEQ_START_TOKEN;
 602
 603         iter = data->stats + (*pos - 1);
 604         if (iter >= data->iter_end)
 605                 iter = NULL;
 606
 607         return iter;
 608 }
 609
 610 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
 611 {
 612         (*pos)++;
 613         return ls_start(m, pos);
 614 }
 615
 616 static void ls_stop(struct seq_file *m, void *v)
 617 {
 618 }
 619
 620 static int ls_show(struct seq_file *m, void *v)
 621 {
 622         if (v == SEQ_START_TOKEN)
 623                 seq_header(m);
 624         else
 625                 seq_stats(m, v);
 626
 627         return 0;
 628 }
 629
 630 static const struct seq_operations lockstat_ops = {
 631         .start  = ls_start,
 632         .next   = ls_next,
 633         .stop   = ls_stop,
 634         .show   = ls_show,
 635 };
 636
 637 static int lock_stat_open(struct inode *inode, struct file *file)
 638 {
 639         int res;
 640         struct lock_class *class;
 641         struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
 642
 643         if (!data)
 644                 return -ENOMEM;
 645
 646         res = seq_open(file, &lockstat_ops);
 647         if (!res) {
 648                 struct lock_stat_data *iter = data->stats;
 649                 struct seq_file *m = file->private_data;
 650                 unsigned long idx;
 651
 652                 iterate_lock_classes(idx, class) {
 653                         if (!test_bit(idx, lock_classes_in_use))
 654                                 continue;
 655                         iter->class = class;
 656                         iter->stats = lock_stats(class);
 657                         iter++;
 658                 }
 659
 660                 data->iter_end = iter;
 661
 662                 sort(data->stats, data->iter_end - data->stats,
 663                                 sizeof(struct lock_stat_data),
 664                                 lock_stat_cmp, NULL);
 665
 666                 m->private = data;
 667         } else
 668                 vfree(data);
 669
 670         return res;
 671 }
 672
 673 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
 674                                size_t count, loff_t *ppos)
 675 {
 676         struct lock_class *class;
 677         unsigned long idx;
 678         char c;
 679
 680         if (count) {
 681                 if (get_user(c, buf))
 682                         return -EFAULT;
 683
 684                 if (c != '0')
 685                         return count;
 686
 687                 iterate_lock_classes(idx, class) {
 688                         if (!test_bit(idx, lock_classes_in_use))
 689                                 continue;
 690                         clear_lock_stats(class);
 691                 }
 692         }
 693         return count;
 694 }
 695
 696 static int lock_stat_release(struct inode *inode, struct file *file)
 697 {
 698         struct seq_file *seq = file->private_data;
 699
 700         vfree(seq->private);
 701         return seq_release(inode, file);
 702 }
 703
 704 static const struct proc_ops lock_stat_proc_ops = {
 705         .proc_open      = lock_stat_open,
 706         .proc_write     = lock_stat_write,
 707         .proc_read      = seq_read,
 708         .proc_lseek     = seq_lseek,
 709         .proc_release   = lock_stat_release,
 710 };
 711 #endif /* CONFIG_LOCK_STAT */
 712
 713 static int __init lockdep_proc_init(void)
 714 {
 715         proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops);
 716 #ifdef CONFIG_PROVE_LOCKING
 717         proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops);
 718 #endif
 719         proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show);
 720 #ifdef CONFIG_LOCK_STAT
 721         proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL, &lock_stat_proc_ops);
 722 #endif
 723
 724         return 0;
 725 }
 726
 727 __initcall(lockdep_proc_init);
 728